The long search for a vegan egg replacer has amounted to—well, a can of beans. Here's everything you need to know about aquafaba, the chickpea byproduct that shines in everything from mayo to meringue.

What is aquafaba?

The viscous water you drain off a can of chickpeas. When whipped, aquafaba rises and thickens into a big, white, foamy cloud that you'd be hard-pressed to distinguish from meringue, and that acquits itself impressively in meringue-based recipes like pavlovas and macarons. Plus cocktails you'd usually drop an egg white into, like this Ramos gin fizz, plus mayonnaise, plus vegan cakes, cookies, and scones.

Why is it called “aquafaba”?

Well, it’s a hell of a better name than “canned bean juice." "Aquafaba" is a relatively recent coinage, devised by a vegan tinkerer in Indiana (more on him below). It joins two Latin words: aqua for water, faba for bean. And it is sometimes abbreviated “af,” as it recently was on a Facebook fan page in the phrase "basic AF meringue." (This may confuse the millennials among us, as they use that abbreviation differently.)

How does it work?

Like chickpea water itself, the science of aquafaba is not 100 percent clear. When you whip egg whites, their proteins trap air and form a colloidal foam, the technical term for what's essentially a meringue—basically, pockets of gas suspended in a liquid. Analysis has identified protein and starches, leached from the chickpeas, in aquafaba. The substance also contains chemical foaming agents called saponins, found in many plants, which may do some of the work here.

Is aquafaba specific to chickpeas?

Not necessarily, but Dever points out that a meringue made from chickpeas will likely look a bit more attractive than one made from, say, black beans. In writing her book she tested other light-colored beans, such as cannellinis and limas, but she was not impressed. "Chickpeas make the strongest aquafaba," she says. She thinks it might be the saponins.

How was aquafaba discovered?

Truly, it was a group effort. Prior generations of vegans have gotten by on commercial egg replacers and good-enough DIY options like bananas (which don't exactly whip) and flax seeds (which unfortunately taste like flax seeds). Aquafaba is a recent discovery, for which the French are partially responsible: in 2014 the French tenor singer Joël Roessel investigated online the possibilities of "vegetal foams," and later, separately, a pair of Gallic daredevils posted a video that showed them making a dessert out of chickpea foam and ganache. Goose Wohlt, the aforementioned vegan in Indiana, refined the notion in early 2015 when he discovered that the meringue he'd been asked to bring to Passover seder could be made simply from chickpea water. (See a timeline here.) By midyear the idea had migrated from vegan blogs to Slate, which published a recipe for aquafaba meringues, and then on to the rest of the media.

Just a little over a year on, aquafaba's got its own home on the Web, run by Wohlt; Dever's forthcoming book, the first devoted to the stuff; and breathless media coverage in publications that run the gamut from Bon Appetit to the New York Times.

Who likes it?

North of 48,000 people on Facebook, for one; that's how many folks belong to Vegan Meringue—Hits and Misses, the bustling Facebook group whose members send in a steady stream of dispatches from their kitchens, where they experiment not just with baked goods but all manner of animal-free snacks. (Hello.) Also vegans in general, creative bakers, people with egg allergies, and bartenders, some of whom claim aquafaba imparts a cleaner taste than egg whites in cocktails.

And big investors, who for several years have sought to fund the hunt for a better egg replacer. The goal of Silicon Valley darling Hampton Creek Foods, for instance, is no less than the removal of factory-farmed eggs from the American market. (Sales in the vegan-mayo market are up to $34 million this year, over $25 million last year, according to the New York Times.) You may remember Hampton Creek from the Great Mayo Wars of 2014 and 2015, when the San Francisco-based startup was sued by Unilever (maker of Hellmann's) for the name of its vegan product Just Mayo (the FDA specifies that products marketed as mayo must contain egg yolks). Striking a blow for vegan condiments everywhere, Hampton Creek prevailed—Unilever dropped the suit—and the company came to a labeling agreement with the feds.

Hampton Creek uses pea protein and modified food starch in its mayonnaise, but earlier this year a New York condiment company called Sir Kensington's debuted Fabanaise, the first aquafaba-based vegan mayo to hit the market; Sir K.'s attracted $8.5 million in funding from investors last year. The company sources its chickpea water from an upstate hummus producer, who used to just throw it away.

How do I use it?

Depends on the recipe you're using (and you may need to reduce the liquid if it's not quite the consistency of egg whites), but the general equivalence is 3 tablespoons where you'd use one egg, 2 tablespoons for one egg white, and 1 tablespoon for an egg yolk.

Has Edith Massey weighed in?

Probably fortunately for her, Ms. Massey is no longer around to see this portent of a future she so feared: a world without eggs.